On my newly restored 300D, the car has been in layup and perpetual modification for almost a year that it never really hit the highway. Two years ago it received a second engine and transmission but because I was driving the car as a "Junker"---a quasi pickup truck-sometimes with one seat only, I never bothered to adjust and fine tune the setup. Half of my vacuum lines were plugged and non functional

After completing the restoration and putting in a new chain, retiming my pump, and adjusting my valves and linkage and unclogging my Fuel Enhancement Solenoid ( the white line that leads to the ALDA) the engine seemed to run well.

So this weekend I got on the highway. I always had heard of a "Poor Man's Tune-Up". So I decided to floor it and I took it to about 95 to see how stable the front end was. ( I had redone the front end completely)

Suddenely the engine coughed or burped. It wasn't something really loud or abrupt, it was more of a gentle burp and then...it just seemed like something changed..it runs so much quieter and smoother now..
It seems much well mannered now and my Auto transmissions shifts are so subtle now....I don't think this could be much different from when it left the factory...so I guess my Poor Man's Tune-Up actually did wonders--but whats the Technical Reason?

You basically blew out all the choking carbon and crud build up in the combustion chambers, cleared out fuel injectors and lines, etc.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

gotta love the italian tuneups

I was being careful not to offend anyone, being of Asian heritage myself, 'course you could say everyone bleeds red when their hands slip on a 1/2" ratchet and you see chunks of flesh gone on a 20 degree day

Increasing the combustion pressure and temperature I think is the primary feature of running hard. It seems to be benificial in a lot of cases. The sensation of the car having a burp or whatever is interesting as well. I wonder if that might be carbon igniting or something simular. Might even be just cleaning out the exhaust for all I know. The pressure is high as well as the temperature is increased. That would upset the applecart for a moment perhaps. It is caused by something. Have always visulised the essential normal cheap tuneup as the really cheap one unless you have paid to have the injectors checked for example. A normal tune up is usually just time. Plus you get quicker at it with experience. The highway thing is perjhaps just icing on the cake as the car will not run it's best unless the other things are checked. It is always nice to hear of an engine running very well. Hopefully your fuel milage will be better now as well. Thats if you can keep your foot out of it with the increased performance.

I think of it kinda like a self-cleaning oven. Hot enough and you vaporize the gunk.

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Paul
2004 E500 4matic; 72,000mi

The term came from old Ferrari's. Back when they had 6 Weber carbs on top of the V12's they used to foul out and run like crap if you idled around town. Run one through the gears and blow the crap out and it ran better.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Good story 240dog.

I sold Fiats around 1980, had a Triumph TR6, ... hmm, do I know you LOL.

The spyders especially (now a 2liter twin-cam) would carbon up, piss all over the spark plugs and stuff, and basically wouldn't start/run well after sitting. The GM knew that I could get them to run properly, toss me a set of keys and off I'd go, down the beltline with it floored until it cleared up.

Would sometimes be kind of funny to bring them back with the undercoating smoking.

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Gone to the dark side

- Jeff